Nowadays—in addition to having sufficient structural stability and resistance to vandalism, etc.—such distribution cabinets have to satisfy further requirements, for example excessive electromagnetic radiation must not be emitted to the surroundings, and, for use in warmer countries in particular, the temperatures in the interior of the distribution cabinet must not rise to too high a level, despite the heat-emitting electrical subassemblies accommodated there, nor must they drop to too low a level.
Such distribution cabinets are, in principle, produced either from metal or from plastic, plastic combining the advantage of less expensive production with the advantage of an electrically non-conductive material, with the result that, even in the case of unplanned contact being established between the housing of the distribution cabinet and an electrical component, there is never the risk of a person who touches the housing from the outside receiving an electric shock.
As far as the sufficient cooling capability of such distribution cabinets is concerned, it is already known for cooling to be effected by air circulation. For this purpose, the body is of a double-walled configuration, the ambient air being able to circulate in the intermediate space between the walls, that is to say enter at the bottom and leave at the top, whereby on the one hand heating-up of the interior by sunlight and on the other hand heat dissipation is effected at the inner wall, which is heated up by the electrical subassemblies in the main space.
In addition, modern distribution cabinets are made EMC-proof, with the consequent result that electromagnetic emission to the outside can only take place within the prescribed limit values.
Some of such distribution cabinets are on private property, but they are often also on public property, so that the respective local authorities have to grant approval for such a distribution cabinet to be installed. As long as the telecommunication companies were also state-owned, this rarely presented any problems; with increasing privatization, the authorities are refusing installation or demand a fee for installation, quite apart from the fact that an approval procedure has to be undergone and takes considerable time.
This problem arises in the case of all distribution cabinets that are to be newly installed, that is to say in particular in development areas, or if there is no longer any space available for technical components, in particular electrical components, in an existing distribution cabinet and a further distribution cabinet should be additionally set up alongside it.
A further, technical problem exists when an existing distribution cabinet is replaced for technical reasons, that is to say for example if the body of an already existing distribution cabinet has to be exchanged to improve the EMC-proof shielding or the cooling capability.
At the same time, it must be remembered that a distribution cabinet generally rests on a base buried deep in the ground, usually made of concrete, latterly also of plastic, into which the buried cables leading to the distribution cabinet and away from it again are led from below, and to which both the usually present installation frame on which the technical components, in particular electrical components, are fastened, is screwed in the same way as the surrounding body. The body is—in particular in the case of the double-shell type of construction mentioned with regard to the inner body—either produced from fixedly interconnected plates, or from a body frame closed by means of paneling. The outer body is fitted on such an inner body at a distance from it by means of paneling.